Involvement of viral and chemical factors with oral cancer in Taiwan.

BACKGROUND: The association between oral squamous cell carcinoma (OSCC) and viral and chemical factors is uncertain. Therefore the correlation of viral and chemical factors with oral cancer in Taiwan was investigated. METHODS: Thirty-seven paraffin-embedded oral cancer biopsies and 36 normal oral tissue specimens were examined by the polymerase chain reaction method for six viruses: HPV, CMV, EBV, HSV-1, HSV-2 and HHV-8. To elucidate the role of arecoline in the oncogenesis of oral cancer, human buccal fibroblasts, oral submucosal fibroblasts and three cancer cell lines KB, GNM and TSCCa were used for MTT cytotoxity assay and flow cytometry DNA content analysis. RESULTS: Two (5.4%) HSV-1-positive and four (10.8%) HPV-positive cases were recognized in oral cancer biopsies. Among the four HPV-positive tissues, two were further typed as HPV-16, one was identified as HPV-18- and HSV-1-positive; and one contained both HPV-16 and HPV-18. One sample presented HSV-1 only. Arecoline, at a concentration lower than 0.8 micro g/ml, increased cell growth (all cell types); at higher concentrations (25-400 micro g/ml) it was cytotoxic. The cell cycle was demonstrated to be altered either by low or high concentrations of arecoline treatment, depending on the cells treated. CONCLUSIONS: The data demonstrated that HPV, HSV-1 and betel quid chewing were significantly associated with OSCC, but HSV-2, CMV, EBV and HHV-8 were not. We suggest that the most determinative factor for oral cancer may be chemical in nature rather than viral infection.